Mouldable hydrocolloid adhesive compositions

ABSTRACT

A mouldable pressure-sensitive hydrocolloid adhesive composition, particularly useful as a medical adhesive, comprising a dispersion of a discontinuous phase of one or more water-soluble and/or water swellable absorbent polymers in a continuous phase comprising a thermoplastic elastomer, a compatible liquid rubber, a polyisobutylene and a low-molecular weight polybutene.

[0001] Hydrocolloid pressure sensitive adhesives are comprised ofdispersions of fluid absorbent materials in pressure sensitive adhesivematrices. These adhesives are well known in medical fields where theyfind use as multifunctional components of medical devices. Inparticular, hydrocolloid adhesives have been extensively utilised in thefields of ostomy care and wound care. In ostomy care, hydrocolloidadhesives are used as the barrier adhesive to hold the pouch in place onthe peristomal skin, and to protect this skin from the excoriatingeffects of body waste. In wound care, hydrocolloid adhesives have beenused as the basis of absorbent dressings for direct application toespecially chronic wounds.

[0002] Hydrocolloid compositions are normally not very flexible orconformable, so that adhesion to movable and curved body parts isdifficult. This lack of flexibility can give rise to problems. Forexample, an ostomy patient with folded or scarred skin in the region ofhis stoma may have difficulty in adhering the hydrocolloid adhesive ofhis pouch to the peristomal skin without getting a leak between the skinand the adhesive. Leaks would allow highly irritating and excoriatingfaeces or urine to come into contact with the skin. The presentinvention is directed at new hydrocolloid adhesives that overcome someof these problems of the prior art adhesives, and extend the utility ofhydrocolloid adhesives into new application areas. Specifically, thisinvention is directed at hydrocolloid adhesives that are mouldable, andthat can be readily adapted to curved and movable body parts.

[0003] The prior art discloses products designed to overcome theshortcomings of inflexible hydrocolloid skin barriers. In the field ofostomy care, adjunct products such as ostomy paste are well known. Suchproducts are useful for protecting and treating the skin contiguous to astoma. The problem of fluid leakage is often aggravated where the skinaround the stoma is irregular, or where folds of skin occur in thisarea. To obtain an improved seal the ostomate can apply a coating ofpaste in a ring around the stoma, allow the paste to dry, and then applythe ostomy pouch over the dried paste.

[0004] A number of ostomy paste compositions appear in the prior art.For example, British Patent Specification 1,430,515 to Hollister, Inc.,U.S. Pat. No. 4,350,785 to Hollister Inc. and European PatentApplication 0048556 A1 to E. R. Squibb & Sons, all describe combinationsof film forming polymers with water absorbable hydrocolloid powders toform a paste which is dispensable from a tube. The problem with thesecompositions is that they have to have a viscosity low enough for theuser to squeeze them from the tubes and therefore they contain asolvent, usually an alcohol such as isopropanol or ethanol, which cansting the skin on application. Also, often the preparation can harden inthe tube, and become difficult or impossible to apply.

[0005] U.S. Pat. Nos. 4,166,051 and 4,204,540 suggest an alternativeapproach to the problem of securing an inflexible ostomy pouch barrieraround the stoma of an ostomy patient with an irregular skin surface.These two patents are directed to homogeneous compositions of a pressuresensitive adhesive component, mineral oil, hydrocolloid gums andcohesive strengthening agents, optionally with added elastomers such asbutyl rubber or medium molecular weight polyisobutylene. The putty-likecompositions can be shaped so as to fill the area between the stoma andthe skin barrier. The compositions can be employed to smooth an area ofthe abdomen around the stoma so as to provide a relatively flat surfaceto which an appliance or skin barrier can be securely attached. Theyhave the advantage over ostomy paste in that they do not containalcohol, and hence do not sting the skin upon application.

[0006] PCT International Application WO 98/17329 to Coloplast disclosesa mouldable mass of a putty-like adhesive for use in connection with anostomy appliance. The composition comprises 1-20 wt % of a blockcopolymer having a major content of di-block copolymer, 5-60 wt % of atackifying liquid constituent and 1-10 wt % of a waxy constituent. Theproduct can be extruded and slit into a rod form that can then be packedinto blisters. The rods can be protected with silicone release paper.Even though the composition is said to be removable from the skin as anintegrated unit, without leaving residues, the composition suffers fromthe drawback of being very sticky, and difficult to use because of itstackiness.

[0007] Eakin Cohesive, a hydrocolloid product available from T. G. Eakin& Sons, Comber, Northern Ireland, is said to be a mouldable, easilyshaped, moisture absorbing skin barrier. According to informationextracted from the Eakin website, http://www.eakin.co.uk, it can bestretched, compressed or moulded to fit the exact shape and size asrequired. Eakin Cohesive contains no active ingredients but is said tocontain a unique carbohydrate which is slowly released while the seal isin place, diluting harmful enzymes, and protecting the skin against bodywastes and fluids such as bile and ileal fluid. The product can be usedas a seal under stoma pouches and appliances, as a packing agent in skinfolds and scars, as a seal around drain tubes and fistulae, and as a“picture frame” around wound edges prior to dressing application. EakinCohesive is, however, not recommended for use in open wounds.

[0008] Eakin Cohesive is functionally comparable to ostomy pastes inthat both products can be moulded and formed to fill up scar areas andhelp to produce a flat skin surface. However, although Eakin CohesiveSeals and ostomy pastes perform the same or similar functions, there arefundamental differences in their performance. Patient studies revealedthat Cohesive Seals are easier to store, handle, mould, apply and removefrom the skin. In general they were quicker and easier to use than theostomy pastes and patients felt more comfortable and confident whenwearing them. Average pouch wear time was increased with use of theEakin Cohesive.

[0009] In comparison, the ostomy pastes were found to be messy to use,left a residue on the skin, and were uncomfortable to remove. Ostomypastes were also noticeably less effective at improving the condition ofred or excoriated skin.

[0010] These patient studies show that a mouldable adhesive or puttysuch as the Cohesive product is a better solution than is ostomy pasteto the problem of uneven skin in the peristomal area. Notwithstandingthese advantages, however, there are several drawbacks with the EakinCohesive product. It preferably has to be warmed to body temperaturebefore use. If the seal is not warmed, it may appear to “crumble” andwill be more difficult to mould. Cohesive is not an integratedhydrocolloid. This means that in the presence of body fluid such asfaeces, urine or wound exudate, the composition breaks down to give asoft gel and becomes amorphous as it gets saturated with fluid. It istherefore an objective of the present invention to make an improvedmouldable hydrocolloid for ostomy care.

[0011] Eakin Cohesive cannot be used in direct contact with wounds. Amouldable hydrocolloid adhesive that could be used in the presence ofexuding wounds would find utility as a wound packing, and provide ameans of extending the duration of wear of conventional hydrocolloiddressings, especially in the presence of wound exudate.

[0012] European Patent EP 0 651 983 B1 discloses a trimmable wounddressing in which a spiral of hydrocolloid is unwound to make a rope ofrectangular cross section which can be used to pack a wound. Thecompositions contain about 20 wt % elastomer and are elastic and notmouldable. On the contrary, they are said to retain their shape in use.Such a structure will expand in the wound as it absorbs wound exudateand, because of its relatively high elastic modulus, may exertconsiderable pressure on the wound bed.

[0013] It is therefore a further objective of the present invention tomake a mouldable hydrocolloid that is suitable for direct contact withwounds, and that will readily conform to wound cavities.

[0014] Ostomates who have a retracted stoma, or whose stoma is difficultto pouch because it is hidden by folds of skin, can have additionalproblems with leaky appliances. In order to help to deal with thisproblem, pouches with convex faceplates have been developed. The convexfaceplate, especially when pressed around the stoma by means of a beltworn around the body and attached to either side of the pouch adhesiveflange, causes the retracted stoma to protrude further into the pouch,thus reducing the propensity for pouch leakage. The use of convexfaceplates in the design of ostomy pouches is becoming more common, andthe markets for them are growing. The manufacture of convex ostomyproducts would be facilitated with the use of mouldable hydrocolloids,which can be formed around a plastic convex plate under the influence ofheat and pressure. It is therefore still a further objective of thepresent invention to formulate a hydrocolloid adhesive that is suitablefor fabrication into an ostomy barrier having a convex faceplate.

[0015] We have found very unexpectedly that hydrocolloid compositionscontaining small amounts of thermoplastic elastomer, and tackified withliquid rubbers for example as disclosed in U.S. Pat. No. 5,274,036,provide the basis for mouldable compositions more mouldable than EakinCohesive and that show no inclination to crumble at room temperature.Some of these compositions are moreover very highly integrated. Specificembodiments of the invention can be used in direct contact with openwounds to provide mouldable compositions useful for wound packing thatallow versatile management of such wounds.

[0016] A mouldable composition according to the invention comprises acontinuous phase consisting of a mixture of a permanently tacky pressuresensitive adhesive, preferably a hot melt adhesive based on astyrene-containing thermoplastic elastomer and a liquid rubber, a lowmolecular weight polyisobutylene and a low molecular weight liquidpolybutene, and dispersed within the continuous phase a discontinuousphase of one or more water soluble and/or water swellable absorbentpolymers.

[0017] Suitable styrene-containing thermoplastic elastomers useful inthe practise of this invention include block copolymers based onstyrene-butadiene, styrene-isoprene or styrene ethylene-butylene. Also,a low styrene synthetic copolymer of butadiene and styrene, commonlycalled SBR rubber, can be used as the thermoplastic elastomer. Theelastomer may consist of linear or radial A-B-A block copolymers ormixtures of these A-B-A copolymers with simple A-B block copolymers.However, the proportion of A-B block copolymers in the mixture of A-B-Aand A-B block copolymers should not exceed about 85% by weight and lowerpercentages would normally be used.

[0018] The A-B-A block copolymers are of the type which consist of Ablocks derived from styrene or one of its homologues and B blocksderived from conjugated dienes, such as butadiene or isoprene, or fromlower alkenes such as ethylene or butylene. The radial A-B-A polymersuseful in this invention are of the type described for example in U.S.Pat. No. 3,281,383 and conform to the general formula (A-B)_(n)X, whereA and B comprise blocks derived from monomers described above inconnection with the A-B-A copolymers, X is an organic or inorganicconnecting moiety having a functionality of at least 2, and n is equalto the functionality of X. The A-B block copolymers useful in thisinvention comprise A and B blocks derived from monomers described abovein connection with the A-B-A copolymers.

[0019] Liquid rubbers useful in this invention are synthetic liquidisoprene rubber, depolymerised natural rubber, carboxyl terminatedsynthetic liquid isoprene-styrene rubber, hydroxyl terminated syntheticliquid isoprene rubber, hydrogenated liquid isoprene rubber, liquidisoprene-styrene copolymer, liquid isoprene-butadiene coplymer andliquid butadiene-styrene copolymer. The liquid rubbers have a molecularweight of about 25,000 to about 50,000. Preferably, the liquid rubbershave a glass transition temperature of less than −50° C., and a meltviscosity at 38° C. of between 500-10,000 poises. It will be appreciatedthat other liquid rubbers known in the art could be useful in thepresent invention.

[0020] The polyisobutylene component is exemplified by the Vistanex LMseries of polyisobutylenes, available from Exxon Chemical Corporation,and which have Flory viscosity average molecular weights in the range35,000 to 70,000, and Brookfield viscosities at 175° C. within the range20,000 and 140,000 mPa.s.

[0021] The low molecular weight polybutene components are exemplified bythe Hyvis series of materials from BP, and by the Parapol series ofproducts from Exxon Chemical Corporation, and which have molecularweights in the range 1000 to 3000, determined using test method AM-I841-86, and kinematic viscosities at 100° C. within the range 180 and3500 cSt, as measured by test method ASTM D445.

[0022] Normally a suitable processing stabiliser would also be includedin the hot melt adhesive component. Suitable stabilisers useful in thepractise of the invention include those indicated for use withstyrene-olefin-styrene block copolymer thermoplastic elastomers such asorganophosphites and the so-called hindered phenols, but any suitablestabilisers may be employed. An example of an organophosphite stabiliseris tris(nonylphenyl) phosphite, available as Polygard HR, manufacturedby Uniroyal. Particularly useful are the hindered phenols, Irganox 1010and Irganox 565, manufactured by Ciba. Irganox 1010 is pentaerythritoltetrakis (3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate. Irganox 565is2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazin-2-ylamino)phenol.Stabilisers may be used separately or in combination, and suitableranges are within 0.3-1.5% by weight based on the total formulation. Thestabilisers are always added to the continuous phase, as is shown in theexamples.

[0023] Other optional ingredients such as tackifiers and plasticisersmay be added to the continuous phase, to modify tack and optimiseadhesion properties.

[0024] The hot melt adhesive component is comprised of the thermoplasticelastomer and the liquid rubber, both as defined above, and issubstantially resin free. Preferably this hot melt adhesive is formed ofa weight ratio of thermoplastic elastomer to liquid rubber of about1:0.5 to about 1:7. The amount of liquid rubber used is varied for thedesired degree of adhesiveness and tackiness of the pressure sensitiveadhesive.

[0025] The amount of hot melt adhesive used in the compositions amountssuch that mouldability is not compromised. The composition shouldpreferably contain at least 1 wt. % of this component but if too muchthermoplastic elastomer is present in the formulation, the compositionswill be too elastic to function as a mouldable material. The preferredupper limit of thermoplastic elastomer in the formulation is 5 wt %,more preferably 3 wt % and most preferably 2 wt %. In addition, theamount of liquid rubber is also important, and a maximum amount ofliquid rubber emanating from the intermediate hot melt adhesivecorresponding to 10 wt % of the total formulation is permitted.Preferably, the maximum amount of liquid rubber is limited to 8 wt % ofthe total formulation.

[0026] The polyisobutylene component should be present at between 25 wt% and 45 wt % of the total formulation, preferably between 30 wt % and40 wt % of the total formulation.

[0027] The low molecular weight polybutene should be present at between5 wt % and 20 wt % of the total formulation, and preferably between 7 wt% and 15 wt %.

[0028] The discontinuous phase comprises one or more hydrophilicpolymers that are soluble or insoluble but swellable in water as themoisture-absorbing component. One or more swellable polymers may bepresent. Suitable insoluble swellable polymers include cross-linkedsodium carboxymethyl cellulose, crystalline sodium carboxymethylcellulose, cross-linked dextran and starch-acrylonitrile graftcopolymer. The swellable polymer may also be a so-called “superabsorbent” material such as starch sodium polyacrylate. Other hydratablepolymers such as gluten and polymers of methyl vinyl ether and maleicacid and derivatives thereof may also be included in the discontinuousphase. Suitable water soluble polymers include sodium carboxymethylcellulose, pectin, gelatine, guar gum, locust bean gum, collagen, karayagum and starch, particularly maize starch, and the like. Thediscontinuous phase should not normally exceed 60% of the total weightof the adhesive, preferably does not exceed 55% by weight of theadhesive, and most preferably does not exceed 50% by weight of theadhesive, and may be comprised of any combination of soluble and/orinsoluble absorbents.

[0029] Optional fillers such as silica and pigments and optional activeingredients such as antimicrobial compounds may also be incorporatedinto the compositions of the invention. Silver sulfadiazine andbenzalkonium chloride represent non-limiting examples of suchantimicrobial ingredients.

[0030] The adhesive compositions of the invention may be prepared asfollows. The thermoplastic elastomer and the liquid rubber component areblended together in a suitable mixer, normally a sigma blade mixer withan extruder discharge. The mixer is heated to about 170° C. A nitrogenflow of about 60 ml/sec through the mixer reduces the possibility ofoxidative degradation of the rubber during processing. About 1% phr of asuitable stabiliser, say Irganox 1010 available from Ciba-Geigy, can beadded at this stage. The thermoplastic elastomer is allowed first toblend in the mixer until it coalesces. Normally a small amount of theliquid rubber, say 10-20%, is added to the whole amount of thethermoplastic elastomer and the liquid rubber is allowed to blend withthe softened thermoplastic elastomer. When all this 10-20% of the liquidrubber has been absorbed, another portion of the liquid rubber is added,say 20-30%, and the liquid rubber is absorbed into thestyrene-olefin-styrene rubber. This is continued until all the liquidrubber is added, when a pourable tacky intermediate adhesive isobtained. The mixer blades are stopped, the direction of the screw isreversed, and the intermediate adhesive is removed from the mixer. It isrun off into suitably release coated containers and allowed to cool.

[0031] The mixer is cleaned, stabilised at 90° C. and the powderyhydrocolloid ingredients are charged to the mixer together with thepolyisobutylene. These are blended until uniform for about 10 minutesand then the previously blended hot melt adhesive component is added andthe mixer temperature is raised to 105° C. After mixing at 105° C. for15 min the temperature of the mixer is dropped to about 80° C. and thelow molecular weight polybutene is added. Mixing is continued normallyfor a further 20 minutes or so. The fully mixed mass is then removedfrom the mixer. It can then be extruded or pressed to the desiredthickness, laminated to suitable substrates and die cut to shapes ifneeded.

[0032] The above manufacturing process has been described with respectto a two-step process in which the hot melt adhesive comprising thestyrene-containing thermoplastic elastomer and the liquid rubber and thestabiliser is first manufactured and isolated and which is thensubsequently used to make the compositions of the invention. It will beappreciated by anyone skilled in the art that no process limitation isimplied and the adhesives of the invention may equally well be preparedin a one-pot process, with no isolation of the intermediate hot meltadhesive.

[0033] The following test methods were used to characterise theproducts.

[0034] Static Absorption of Hydrocolloids.

[0035] To determine the amount of fluid uptake into a known surface areaof hydrocolloid adhesive.

[0036] Procedure

[0037] Cups with flanges for use in determination of Moisture VapourTransmission are suitable for use in this test. Laminate release linerto the upper flange of the cup with the double coated tape. This is thecontact zone for the hydrocolloid. Fill the cup with 30 ml NaCl solution(0.9% wt). Cut a sample of hydrocolloid of about the same size as theouter cup diameter. Weigh the sample (W₁). Laminate the sample to thecup, making sure that the seal between the hydrocolloid sample and thecup is water tight. Turn the cup upside down and put it in the oven at37° C. for 24 hours. Cool down. Remove the hydrocolloid from the cup andreweigh (W₂). Calculate the water fluid absorption (g/sq. m. 24 h) usingthe formula:

absorption=(W ₂ −W ₁)/0.002375

[0038] where the area of the hydrocolloid in contact with salt solutionis 0.002375 sq. m.

[0039] Determination of the Integrity

[0040] The integrity of a hydrocolloid is defined as its ability toresist breakdown by biological fluids. The test measures the weightpercentage of hydrocolloid retained after exposure to saline underspecified conditions.

[0041] Procedure

[0042] Condition the hydrocolloid samples at 23±1° C. and 50±2% relativehumidity for 24 hours. Cut circular samples from the hydrocolloid sheet2.54 cm diameter. Weigh and record the samples (W_(i)). Place eachsample in a 120 ml (4 oz) bottles with screw caps (Vel Catalog Number1198017) with 50 ml physiological saline (NaCl 0.9% wt in water), capthe bottles and agitate on a bottle shaker at maximum speed for a periodof 18 hrs. Remove the samples and dry them in a circulating air oven at50° C. and 50% relative humidity until dry. This usually takes about 24hours. Reweigh the sample (W_(f)). The Integrity Value of the sample iscalculated using the following equation:${{Integrity}\quad {Value}\quad (\%)} = {100 \times \frac{\left( W_{f} \right)}{\left( W_{i} \right)}}$

[0043] Note: The test may be run with hydrocolloid with or withoutcarrier. However, the result may be affected, and suitable controlsamples should always be included.

[0044] Determination of Mouldability

[0045] Assessment of the mouldability of the hydrocolloid materials wasmade using the test methods described in Adhesives Age, September 1997,pp 18-23. The equipment used was a probe tester manufactured by StableMicro Systems, Godalming, Surrey, England, driven by custom designedsoftware.

[0046] Using the equipment, the energy absorbed by the mouldableadhesive as the probe penetrated the adhesive was determined by atransducer. The probe is moved up and down by a rotating screw which isdriven by a stepping motor. The displacement of the probe was measuredthrough the motor rotation.

[0047] For each measurement, the probe was a stainless steel ball of25.4 mm in diameter. The compressive force was 4.5N and the test speedwas 0.04 mm/sec.

[0048] The raw materials used in the examples are as follows:

[0049] Escorez 2203LC—Exxon Chemical—Tackifying resin

[0050] Regalite 1100—Hercules Chemical—″ ″

[0051] Adtac LV-E—Hercules Chemical—″ ″

[0052] LVSI-101—Kraton Polymers—Liquid rubber

[0053] Vector 4111—Exxon Chemical—Thermoplastic elastomer

[0054] Kraton D-1161NS—Kraton Polymers—″ ″

[0055] Irganox 1010—Ciba Chemicals—Antioxidant

[0056] Parapol 1300—Exxon Chemical—Polybutene

[0057] Vistanex LMMS—Exxon Chemical—Polyisobutylene

[0058] Maize Starch—National Starch and Chemical

[0059] Pectin USP100—Hercules Chemical

[0060] Blanose 7H4XF—Hercules Chemical—Sodium carboxymethyl cellulose

[0061] Aquasorb A500—Hercules Chemical—Sodium carboxymethyl cellulose

[0062] Kaydol Mineral Oil—Witco Chemical

[0063] The invention will now be further described with reference to thefollowing non-limiting examples. While Examples 6 through 12 illustratethe application of the present invention to constructions generallysuitable for use in ostomy care, and Examples 13 through 27 showformulations generally more suitable for use in wound care applications,it will be understood that no limitation is implied by this separation.

EXAMPLE 1

[0064] This example illustrates preparation of the intermediate hot meltadhesive. wt % total Amount, gm LVSI-101 79.37 400 Kraton KD-1161N 19.84100 Irganox 1010 0.79 4 100.00 504

[0065] A Z-blade mixer of 1 kg. capacity was purged with nitrogen gasand heated to 160° C. The speed of the front, faster, blade was 30 rpm.The Kraton KD-1161N and the Irganox 1010 were charged to the Mixer at160° C., and the mixer was started. After mixing for 5 minutes, therubbery crumb coalesed, and 50 gm of the LVSI-101 was added withcontinued mixing and nitrogen purging. After a further ten minutes, thetemperature was raised to 170° C. and the mixer front blade speedincreased to 47 rpm. The LVSI had at this point completely mixed withthe rubber, and a further 51 gm of LVSI was added. Ten minutes later,after blending of the second portion of the LVSI, a further 48 gm ofLVSI was added, and mixed for a further 10 minutes. In this way,approximately 50 gm portions of the charge of LVSI were added every 10minutes until all the 400 gm had been added. 15 minutes later, theintermediate adhesive was dumped from the mixer. The total time for thisoperation was about 90 minutes.

EXAMPLE 2

[0066] In a similar way to Example 1, the following adhesive was made.wt % total Amount, gm LVSI-101 59.54 300 Kraton KD-1161N 39.68 200Irganox 1010 0.80 4 100.02 504

EXAMPLE 3

[0067] This example illustrates the preparation of a more conventionalhot melt adhesive used in the formulations. The mixer was purged withnitrogen gas and heated to 160° C. The Regalite R1100, 200 gm. and theIrganox 1010 were charged to the mixer at 160° C., and warmed for 15minutes. The amount of Vector 4111 triblock S-I-S elastomer from ExxonChemical was added. After mixing for 70 minutes, the remainder of theRegalite and the Adtac LV-E were added over 35 minutes. The adhesive wasrun off from the mixer into release coated containers and cooled. wt %total Amount, gm Regalite R1100 45.08 362 Irganox 1010 0.75 6 Vector4111 36.11 290 Adtac LV-E 18.05 145 100.0 803

EXAMPLE 4-5

[0068] In an analogous fashion to Example 3, two further intermediateadhesives were prepared having the following compositions: wt % totalAmount, gm Example 4 Escorez 2203 LC 41.69 336 Irganox 1010 0.74 6Kraton D-1161NS 37.72 304 Adtac LV-E 19.85 160 100.0 806 Example 5Regalite R1100 46.12 320.0 Irganox 1010 2.39 16.6 Kraton D-1161NS 33.04229.2 Mineral Oil 18.45 128.0 100.0 693.8

EXAMPLE 6

[0069] This example illustrates the manufacture of a mouldablehydrocolloid formulation suitable for use by ostomy patients as a fillerfor uneven skin under an ostomy pouch, and for conversion to a convexfaceplate pouch barrier construction.

[0070] Maize Starch (96 gm), Pectin USP100 (40 gm) and sodiumcarboxymethyl cellulose, Blanose 7H4XF (100 gm) were charged to alaboratory scale 1 l. Z-blade mixer, previously heated to 90° C. Afterblending the powders for 2 minutes, Vistanex LMMS polyisobutylene (164gm) was added, and mixing was continued for 10 minutes, at the end ofwhich time the temperature of the mixer was raised to 105° C. The hotmelt adhesive 2-18A from Example 1 (40 gm) was added to the mixer, andblending was continued for a further 10 minutes, at the end of whichtime the temperature in the mixer was dropped to 85° C. Parapol 1300 (40gm) was added gradually to the contents of the mixer and kneading wascontinued for 20 minutes after the final addition of the Parapolingredient. The mixer was stopped and the hydrocolloid was removed. Itwas extruded in a laboratory extruder between two silicone coatedrelease papers to a web of 2.4 mm thickness.

[0071] The mouldable hydrocolloid was evaluated and found to have anabsorbency of 7742 Gms/sq. m./24 hrs, and an integrity of 93.8%. Theresults are shown in TABLE 1.

EXAMPLES 7-10

[0072] In an analogous fashion to Example 6, mouldable hydrocolloids ofExamples 7-10 were made and evaluated, with the results shown in theTABLE 1 below. TABLE 1 Formulation, wt % Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10Hot Melt of 1 2 3 5 4 Example LVSI-101 6.61 4.96 — — — Kraton 1.65 3.31— 2.75 3.14 D-1161NS Vector 4111 — — 3.01 — — Irganox 1010 0.07 0.070.06 0.20 0.06 Regalite 1100 — — 3.76 3.84 — Adtac LV-E — — 1.50 — 1.65Mineral Oil — — — 1.54 — Escorez 2203 — — — — 3.47 LC Vistanex LMMS34.17 34.17 34.17 34.17 34.17 Pectin USP100 8.33 8.33 8.33 8.33 8.33Blanose 7H4XF 20.83 20.83 20.83 20.83 20.83 Maize Starch 20.00 20.0020.00 20.00 20.00 Parapol 1300 8.33 8.33 8.33 8.33 8.33 PropertiesLiquid rubber: 4.00 1.50 (1.75) (1.40) (1.86) Thermoplastic elastomer,wt/wt Static 7742 6379 8295 7061 8290 Absorption Gms/sq. m./ 24 hrsIntegrity, % 94 12 20 10 10 Thickness, mm 2.4 2.0 2.0 2.0

[0073] The results from TABLE 1 are striking and show the surprisingresult that, at the low level of rubber used, only the one intermediatehot melt adhesive used in Example 6 serves to integrate thehydrocolloid. Example 7 contains a higher amount of S-I-S thermoplasticelastomer, and a higher thermoplastic elastomer:liquid rubber ratio thandoes the adhesive of Example 6. The mouldable adhesives from comparativeexamples 8, 9 and 10, which have no liquid rubbers, but rather containconventional tackifying agents, have very little integrity. The datashow that, in the adhesive system exemplified by Example 6, an upperrubber concentration limit of 2% by weight, and a thermoplasticelastomer:liquid rubber ratio of less than 1:1.5, and preferably 1:4,appears necessary to get integration.

EXAMPLE 11

[0074] The mouldable hydrocolloid from Example 6 was compared with theEakin Cohesive product. The data on each are given in TABLE 2. It can beclearly seen that the integrity of the Eakin product is close to zero(the 10% integrity measured actually derives from the residual plasticfilm that was laminated to the product for the test). Typicalpenetration data are shown in the curves of FIG. 1. It can very clearlybe seen that the energy absorbed by the hydrocolloid of Example 6 is fargreater than that of the comparatively rigid Eakin Cohesive product,demonstrating the softness and easier mouldability of the hydrocolloidof Example 6. TABLE 2 shows also the greater penetration (21.5 mm) ofthe Example 6 adhesive by the stainless steel probe at the force of4.5N, compared to that with the Eakin Cohesive product (18.0 mm).Because of the poor integrity of the Cohesive, its absorption could notbe measured, as the adhesive melts into a soft, low viscosity gel. Theother measured properties of the two adhesives are comparable. TABLE 2Eakin Cohesive Ex. 6 Reverse tack, N/25 mm 9.1 12.0 Peel Adhesion 90°Teflon, N/25 mm 2.6 4.8 Shear Adhesion 0.5 kg, min 18 20 Thickness, mm2.60 2.45 stat. Absorption, gm/sq. m/24 hr Not Measurable 7566Penetration/Softness, mm 18.0 21.5 Integrity, % 10 98

[0075] The static absorption and the integrity of Example 6 in TABLE 2differ slightly from the values shown for Example 6 in TABLE 1, becausethey were measured on a different batch of mouldable adhesive.

EXAMPLE 12

[0076] The hydrocolloid from Example 6 is made into a convex body-sideflange of a two piece ostomy-device, illustrated in FIG. 2. Withreference to the FIG. 2, component 13 is an injection moulded body-sideflange piece, with an integral flange circumferential to the outer edgeof the convex form. The body-side flange is moulded from a blend of lowmolecular weight polyethylene and ethylene-vinyl acetate copolymer.Component 11 is an annular collar die cut from treated, waterproofedSontara 8000 non-woven fabric which is coated with medical grade acrylicpressure sensitive adhesive on its underside, and is available as LassoSA72 from Smith and Nephew, which can overlay the circumferential flangeof the connector. Component 12 is the mouldable hydrocolloid adhesive,moulded to the underside of the convex flange and the non-woven overlay,using a matched die set which is heated to 100° C. in a 100 ton Bradleyand Turton upstroking press. A vacuum moulded plastic protector, notshown in FIG. 2, with silicone release coating on its concave surface,can be made to fit on the underside of the construction to protect theadhesive until removal by the end-user.

EXAMPLES 13-27

[0077] Examples 13-27 show the formulation of mouldable hydrocolloidssuitable for direct contact with wounds. The results are shown in TABLES3 and 4. Generally, starch is not considered suitable for contact withwounds since it is likely to be a nutrient for any pathogenic organismspresent. Aquasorb A500, crystalline sodium carboxymethyl celluloseavailable from Aqualon division of Hercules Chemical Company, generallywas used as a replacement for the starch in these compositions. Theformulations having the highest degree of integrity were integrated witha hot melt adhesive having a thermoplastic elastomer:liquid rubber ratioof 1:4. Examples 24-27 in comparison, with the same amount of hot meltadhesive but with a 1:1.5 ratio of thermoplastic elastomer:liquidrubber, were not found to have such high integrity. It was also foundthat the highest integrity products had, as the absorbent medium, blendsof soluble and insoluble absorbents. Nevertheless, these compositionsare also useful as mouldable hydrocolloid adhesives.

[0078] Example 23, when sterilised using gamma radiation at 25 KGy,showed excellent retention of integrity, and a moderate but stillacceptable reduction in absorption capacity. The gel resulting fromabsorption of fluid is soft, will readily conform to the surface of awound bed and will not cause significant pressure within the wound.TABLE 3 Formulation, wt % Ex. 13 Ex. 14 Ex. 15 Ex. 16 Ex. 17 Ex. 18 Ex.19 Ex. 20 Hot Melt of 1 1 1 1 1 1 1 1 Example LVSI-101 6.61 7.94 6.616.61 4.76 4.71 6.53 4.76 Kraton D-1161NS 1.65 1.98 1.65 1.65 1.19 1.181.63 1.19 Irganox 1010 0.07 0.08 0.07 0.07 0.05 0.05 0.07 0.05 VistanexLMMS 34.17 35.00 35.00 35.00 35.00 34.57 34.57 35.00 Pectin USP100 — —8.00 8.00 8.00 7.90 7.90 17.00 Blanose 7H4XF — — 20.00 20.00 20.00 19.7519.75 32.00 Aquasorb A500 49.16 45.00 17.00 18.67 17.00 20.74 16.79 —Parapol 1300 8.33 10.00 11.67 10.00 14.00 11.11 12.76 10.00 PropertiesLiquid rubber: 4.00 4.00 4.00 4.00 4.00 4.00 4.00 4.00 Thermoplasticelastomer, wt/wt Static Absorp 11760 12027 7992 7810 7478 8214 7512 8518Gms/sq. m./24 hrs Integrity, % 40 35 38 48 9 9 29 7 Thickness, mm 2.02.0 0.8 0.8 0.8 0.8 0.8 1.0

[0079] TABLE 4 Formulation, wt % Ex. 21 Ex. 22 Ex. 23 Ex. 23 Ex. 24 EX.25 Ex. 26 Ex. 27 Hot Melt of 1 1 1 1 2 2 2 2 Example Non- sterilesterile LVSI-101 6.61 7.94 7.94 7.94 5.95 5.95 5.95 5.95 Kraton D-1161NS1.65 1.98 1.98 1.98 3.97 3.97 3.97 3.97 Irganox 1010 0.07 0.08 0.08 0.080.08 0.08 0.08 0.08 Vistanex LMMS 35.00 35.00 35.00 35.00 35.00 35.0030.00 32.50 Pectin USP100 15.00 15.00 8.00 8.00 — 8.00 — 8.00 Blanose7H4XF 30.00 30.00 20.00 20.00 — 20.00 — 20.00 Aquasorb A500 1.67 — 17.0017.00 45.00 17.00 45.00 17.00 Parapol 1300 10.00 10.00 10.00 10.00 10.0010.00 15.00 12.50 Properties Liquid rubber: 4.00 4.00 4.00 4.00 1.501.50 1.50 1.50 Thermoplastic elastomer, wt/wt Static Absorp 7562 78199006 6547 11865 9802 11254 7806 Gma/sq. m./24 hrs Integrity, % 59 70 7874 10 10 10 10 Thickness, mm 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0

1. A mouldable pressure-sensitive hydrocolloid adhesive compositioncomprising a dispersion of a discontinuous phase of one or morewater-soluble and/or water-swellable absorbent polymers in a continuousphase comprising: (a) a thermoplastic elastomer; (b) a liquid rubbercompatible with the elastomer (a), the weight ratio of liquid rubber (b)to elastomer (a) being in a range from 0.1:1 to 10:1; (c) 20-50 wt. %,based on the total formulation, of a polyisobutylene having a viscosityaverage molecular weight in a range from 25,000 to 100,000; and (d) 3-20wt. %, based on the total formulation, of a low-molecular weightpolybutene, wherein the content of thermoplastic elastomer constitutesnot more than 10 wt. % of the total formulation.
 2. A compositionaccording to claim 1 wherein said liquid rubber has a molecular weightof 25,000 to 50,000.
 3. A composition according to claim 1 or claim 2wherein the polyisobutylene has a viscosity average molecular weight ina range from 35,000 to 70,000.
 4. A composition according to anypreceding claim wherein the low molecular weight polybutene has amolecular weight of 1,000 to 3,000 according to ASTM D445.
 5. Acomposition according to any preceding claim wherein the weight ratio ofthermoplastic elastomer to liquid rubber is in a range from 1:0.5 to1:7.
 6. A composition according to any preceding claim wherein thecontent of thermoplastic elastomer, based on the total composition, isnot more than 5 wt. %.
 7. A composition according to claim 6 whereinsaid content of thermoplastic elastomer does not exceed 2 wt. %.
 8. Acomposition according to any preceding claim wherein the content ofliquid rubber emanating from the hot melt adhesive component (b) doesnot excess 10 wt. % of the total formulation.
 9. A composition accordingto any preceding claim which comprises from 30-40 wt. %, based on thetotal formulation, of said polyisobutylene component.
 10. A compositionaccording to any preceding claim which contains from 7-15 wt. % of saidlow molecular weight polybutene.
 11. A composition according to anypreceding claim wherein the discontinuous phase comprises not more than60 wt. % of the total composition.
 12. A convex body-side face plate foran ostomy device, having formed thereon a pressure-sensitive adhesivelayer of a composition according to any preceding claim.
 13. A method ofmaking a mouldable adhesive composition according to any one of claims 1to 11 which comprises the steps of blending the thermoplastic elastomer(a) with the liquid rubber (b) to form an intermediate hot melt adhesivecomponent and blending the polyisobutylene, the intermediate hot meltadhesive and the low molecular weight polybutene with the water-solubleand/or water-swellable absorbent polymer.